This invention relates generally to novel and improved brake equipment for rail vehicles and more particularly to computer controlled brake equipment located on the locomotive and arranged to control the application and release of the brakes of such locomotive, any trailing locomotive, and any cars coupled to either.
Prior art brake equipment for locomotives has typically been implemented with mechanical and pneumatic hardware, as, for example, the 26-L brake equipment of New York Air Brake Company of Watertown, N.Y. As illustrated in FIG. 1, this prior art brake equipment employs as major components a 26-C brake valve 30 including an independent brake valve SA-26, a 26-F control valve 33 and a J relay valve 37 interconnected with various pneumatic pipes represented by solid lines. The brake valve 30 responds to movement by the train operator of an automatic brake handle 31 to regulate pressure in a brake pipe 40 by means of an equalization reservoir 36 and a brake pipe relay in the brake valve 30 for application and release of brakes on the locomotive, the brakes of any trailing locomotive and the brakes of cars coupled to either (train brakes).
The automatic brake handle has six positions as illustrated by the sector diagram in FIG. 2 and defined as follows:
a) The Release position is for charging the brake equipment and releasing the train brakes. PA1 b) In the Minimum Reduction position, brake pipe pressure is reduced a minimum amount so as to initiate quick service on the train brakes (typically 4-6 psi brake pipe reduction), and lightly apply the train brakes. PA1 c) The sector or zone between the Minimum Reduction and Full Service positions is the service zone. As the automatic brake valve handle is moved through this zone from Minimum Reduction toward Full Service, brake pipe pressure is reduced proportionally to 23-26 psi with the handle at the Full Service position, a full service brake application is obtained. PA1 d) In addition to providing full service brake application as with the brake valve handle in the Full Service position, Suppression of overspeed control and safety control application is obtained in the suppression position. PA1 e) The handle is movable to the Handle Off position as for trailing units of a multiple unit locomotive or for locomotive's being towed "dead" in a train. The handle off position is also used for "overreductions" allowing brake pipe to be reduced further than attainable in the Full Service position. Thus assuring full train brake applications. PA1 f) The Emergency position is used for making brake valve emergency brake applications and results in brake pipe exhaust and brake pipe venting at the highest rate of reduction.
The brake valve 30 also responds to movement of an independent brake handle 32 by the train operator to control the application and release of the locomotive brakes independently of the train brakes and for releasing an automatic brake application of the locomotive independently of the train brakes by way of the 26-F control valve 33 and the J relay 37.
The independent brake handle 32 has two extreme positions, Release and Full Application separated by an application zone as shown in FIG. 2. As the handle is moved from the Release position through the application zone toward the Full Application position will apply the locomotive brakes. The independent handle 32 can be depressed so as to cause the release of any automatic brake application existing on the locomotive (due to operation of the automatic brake handle 31). This is effected via the 26-C brake valve 30 and the 26-F control valve 33. If the independent brake handle 32 is in an Application position, the locomotive brake will be applied according to the higher of independent or automatic brake.
The 26-F control valve 32 and auxiliary reservoir 36 respond to service and emergency rates of brake pipe pressure reduction (brake applications) to control the locomotive brake cylinder pressure via the J relay valve 37. The 26-F control valve 33 also responds to a brake release operation of the independent brake handle 32 to control locomotive brake cylinder pressure to release the locomotive brakes following an automatic brake operation at the service rate developed by operation of the automatic brake handle 31. A key element of the 26-F control valve 30 is a double check valve 34 which applies to the J relay valve 37 the higher of the pressures developed by the 26-F control valve 33 or by the independent application and release pipe 42.
The J relay valve 37 is a volume amplifier that operates to translate the pressure at a smaller volume input to a desired pressure at a larger volume output. As the desired output pressure can differ for different locomotive (different sized brake cylinders), it has been necessary to select a particular J relay valve for a particular locomotive specification.
The P2-A valve 35 is a brake application or penalty valve responsive to unsafe conditions to effect brake application at the full service rate. For instance, the P2-A valve is illustrated as responding to an overspeed condition and/or to a foot pedal fault (absence of foot pressure on the foot pedal).
The brake equipment also includes a multiple unit valve 38 enabling the locomotive to be united with other locomotives as either a lead, trail or dead unit. The multiple unit valve 38 of a lead unit serves to signal trail units via independent brake application and release pipe 42 and an actuating pipe 43. In the lead position, multiple unit valve 38 connects the actuating pipe signal from brake valve 30 to the control valve 33 and actuating pipe 43 and connects the independent application and release signal from the brake valve 30 to the independent application and release pipe 42.
The prior art brake equipment is costly to manufacture as it requires substantial iron and aluminum castings for each of the pneumatic valves and is costly to install as it requires numerous pipe interconnections.
Computerized brakes are well known as shown by U.S. Pat. No. 4,402,047 to Newton et al. In this computerized brake control system, the computer calculates the desired brake cylinder pressure from commanded brake signals, vehicle weight, vehicle speed and dynamic braking and compares the desired brake cylinder pressure with the actual brake cylinder pressure. Then it controls the fluid brake system to cause the actual brake pressure to be substantially equal to the desired brake pressure. As illustrated in FIG. 2 of that patent, the brake control manifold 40 has an electromagnetically controlled apply valve 46 and release valve 48 under the control of computer to cause the desired brake cylinder pressure to match the desired brake cylinder pressure.
Another system which shows the use of magnetic valves for applying and releasing brake pressure is U.S. Pat. No. 4,652,057 to Engle, et al. Single control handle 76 is used in combination with a control panel 102 and a display 96. In both systems, the electromagnetically controlled valves control the specific pressure applied to the brake cylinders from a reservoir and does not control the pressure within the reservoir.
Prior systems have also included a substantial amount of fluid tubing which is costly to build and maintain. Similarly the interlocks between the propulsion and braking system have been mechanical and also a function of the operator.
Thus this is an object to present invention to provide a novel computer interfaced for a computer controlled rail brake equipment.
Another object of the present invention is to provide a braking system which will guarantee full service application for any initial computer brake pipe pressure charge. A further object is to provide standardization of locomotive hardware that would not require alternate parts.
Still a further object of the present invention is to provide a computer controlled railway brake system with improved interlocks.
These and other objects of the present invention are achieved by providing a computerized locomotive control system receiving as inputs electrical signals representing automatic an independent braking control signals and a computer for determining, from said input signals, electrical signals representing desired equalization reservoir pressure, desired independent application and release pressure and desired actuating pressure. A first electro-pneumatic valve controls the pressure in the equalization reservoir in response to the desired equalization pressure. A second electro-pneumatic valve controls the pressure on the independent application and release pipe in response to the desired independent application release pipe pressure signal. A third electro-pneumatic valve controls the pressure on the actuating pipe in response to the desired actuating pressure signal. Thus the system has basically used a computer to emualate the 26C brake valve usable with automatic and standard independent brake handles.
Input signals are provided representing predetermined equalizing reservoir release pressure. The computer determines a corresponding full service pressure from the predetermined equalizing reservoir release pressure and determines a proportional desired equalizing reservoir signal in the range between the equalizing reservoir's predetermined release and corresponding full service pressures from the automatic braking control signals Thus the braking signal is proportional to the predetermined reservoir release pressure and not dependent merely on the brake handle position. This improves train brake handling by making the Full Service brake position actual full train brake application.
The system also includes a fourth electro-pneumatic valve for controlling the pressure in the control reservoir. The computer determines the desired control reservoir pressure from pipe pressures alone or incombination with braking control signals to control the fourth electro-pneumatic valve. Electric signals representing brake pipe pressure, the independent application and release pipe pressure and the actuating pipe pressure are provided to computer.
The computer also receives electrical signals identifying the brake cylinder valve and uses this in determining the appropriate reservoir pressure. This allows the combination for J relays of various capacities. The locomotive brake cylinder circuit also includes pneumatic circuit for pneumatically controlling the brake cylinder by applying and releasing emergency pressure independent of the control reservoir as well to limit the brake cylinder pressure. A fluid switchover circuit is also provided determining whether the fourth electro-pneumatic valve or the brake pipe will control pressure in the control reservoir. A brake pipe disconnect valve is also provided in responsive to the switchover to disconnect the brake pipe valve from the brake pipe.
The computer also receives electrical signals representing a penalty condition and determines a service brake application pressure as the desired equalization reservoir pressure in response to a penalty condition Additionally an electromagnetic cut-off valve is provided and controlled by the computer in response to an emergency brake application to cut-off the brake pipe from the brake pipe valve. If the train is in the trailing mode, the computer also disconnects the brake pipe valve from the brake pipe using the cut-off control.
As safeguards, the computer determines, for absence of an automatic braking control signal, a service reduction of a desired equalizing reservoir pressure signal to at least the full service application. The computer also determines, for absence of an independent brake control signal, a brake release desired independent release pressure signal. The first electro-pneumatic valve reduces the pressure in equalizing reservoir to at least full-service for absence of a desired equalization reservoir pressure. Second and third electro-pneumatic valves lap for absence of a desired independent application and release pressure signal and actuating signal respectively.
The computer also provides a plurality of electrical interlocks depending upon the position of the handles as well as ignoring the position of the handles. Upon determination of an emergency braking condition, the computer transmits an idle condition signal for the throttle and will not transmit any propulsion signals until the throttle handle is also placed in the idle position. The computer also delays the transmission of predetermined signals from the throttle when switching between propulsion and dynamic braking. Also, the computer, when the throttle handle switches from forward to reverse, prevents transmitting propulsion control signals until the locomotive speed in below a predetermined speed. If the computer senses that the locomotive is being switched between the leading and trailing modes, it does not transmit any control signals until the position control signals represent neutral or idle positions for the automatic and interdependent brake controls and the throttle. Also in switching between leading and trailing modes, the locomotive speed must be zero.
As with the braking signal, the computer can determine a proportional propulsion signal between zero and an inputted maximum speed for the appropriate throttle position. If the system is set for the trailing mode, the computer does not produce any propulsion or dynamic braking signals. The computer can also be programmed to produce automatic speed control.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.